Causal asymmetry of classical and quantum autonomous agents
Why is it that a ticking clock typically becomes less accurate when subject to outside noise but rarely the reverse? Here, we formalise this phenomenon by introducing process causal asymmetry—a fundamental difference in the amount of past information an autonomous agent must track to transform one stochastic process to another over an agent that transforms in the opposite direction. We then illustrate that this asymmetry can surprisingly reverse when agents possess a quantum memory. Thus, the spontaneous direction in which processes get ‘simpler’ may be different, depending on whether quantum information processing is allowed or not.
Authors
- Spiros Kechrimparis (ORCID: https://orcid.org/0000-0002-8731-9334)
- Mile Gu (ORCID: https://orcid.org/0000-0002-5459-4313)
- Hyukjoon Kwon (ORCID: https://orcid.org/0000-0001-5520-0905)
Institutions
- Centre for Quantum Technologies (SG)
- Korea Institute for Advanced Study (KR)
- Nanyang Technological University (SG)
- Mount Elizabeth Novena Hospital (SG)
Publication Details
- Journal
- npj Quantum Information
- Published
- 2026-09-01
- DOI
- https://doi.org/10.1038/s41534-026-01335-7
- Primary Topic
- Quantum Mechanics and Applications
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Silicon Valley Community Foundation
- Fetzer Institute
- Foundational Questions Institute
- National Research Foundation
- Agency for Science, Technology and Research
- National Research Foundation Singapore
- Ministry of Education - Singapore
- Bộ Giáo dục và Ðào tạo
- Centre for Quantum Technologies
- Korea Institute for Advanced Study